The present invention relates to the field of blister packages. Blister packages include a tub for containing a product and a cardboard backing. The tub is typically made of clear plastic so that the product can be seen.
In many conventional blister packages the tub is glued to the cardboard backing. The blister package is opened by tearing the cardboard away from the plastic tub. A problem with conventional glued blister tubs is that once the package is opened it cannot be resealed. If items are kept in an opened blister package they are prone to fall out and become lost.
Several known blister packages have a tub which is slidable relative to the backing so that after the blister package is first opened it can be closed again and used to contain the remaining product. A slidable blister tub is disclosed in U.S. Pat. No. 3,467,248 to Mackowicki. The tub has laterally protruding flanges which engage a pair of channels. To remove the product, a user slides the tub so that the tub opening is beyond the cardboard backing. After the desired items are removed, the tub is moved back to store the remaining product.
A problem with the blister package disclosed in U.S. Pat. No. 3,467,248 is that the tub is not restrained from sliding. The blister package can be opened quickly and presents an easy target for thieves.
A further problem with the blister package disclosed in U.S. Pat. No. 3,467,248 is that the tub can become completely disengaged from the cardboard backing. If the tub becomes inadvertently disengaged from the cardboard backing some of the product will probably be spilled. The tub can become disengaged when a user is removing items and inadvertently slides the tub beyond the flange to channel engagement. The tub can also become disengaged during transportation since the tub is not restrained from sliding.
A further problem with the blister tub disclosed in U.S. Pat. No. 3,467,248 is that a user cannot tell whether the blister package has already been opened. Consumers often want to know whether a package has been opened, particularly with edible items, to avoid products which have been tampered with.